1. Field of the Invention
The present general inventive concept relates to an inkjet printhead and a method of manufacturing the inkjet printhead, and more particularly, to a thermal inkjet printhead having a uniformly formed ink feed hole and a method of manufacturing the thermal inkjet printhead.
2. Description of the Related Art
Inkjet printheads are devices used to form color images on printing mediums by firing droplets of ink onto a desired region of a corresponding printing medium. Inkjet printheads can be classified into two types depending on an ink ejecting method used: thermal inkjet printheads and piezoelectric inkjet printheads. The thermal inkjet printheads generate bubbles in ink by using heat and eject the ink utilizing an expansion of the bubbles, and the piezoelectric inkjet printheads eject ink using a pressure generated by deforming a piezoelectric material.
The ink droplet ejecting mechanism of the thermal printhead will now be more fully described. When a current is applied to a heater formed of a resistive heating material, heat is generated from the heater to rapidly increase a temperature of adjoining ink to about 300° C. As a result, a bubble is created and as the bubble expands it increases a pressure of ink in an ink chamber of the thermal printhead. This pushes the ink out of an ink chamber through a nozzle in a form of a droplet.
FIG. 1 illustrates a schematic sectional view of a conventional thermal inkjet printhead. Referring to FIG. 1, the conventional inkjet printhead includes a substrate 10 on which a plurality of material layers are stacked, a chamber layer 20 disposed above the substrate 10, and a nozzle layer 30 disposed on the chamber layer 20. The chamber layer 20 includes a plurality of ink chambers 22 filled with ink that is to be ejected. The nozzle layer 30 includes a plurality of nozzles 32 to eject ink. An ink feed hole 11 is formed through the substrate 10 to supply ink to the ink chambers 22. The chamber layer 20 further includes a plurality of restrictors 24 connecting the ink chambers 22 and the ink feed hole 11.
The substrate 10 can be formed of a commonly used silicon substrate. An insulating layer 12 is formed on the substrate 10 to insulate the substrate 10 from heaters 14. The insulating layer 12 may be formed of a silicon oxide. The heaters 14 are formed on the insulating layer 12 to create bubbles by heating ink filled in the ink chambers 22. Electrodes 16 are formed on the heaters 14 to apply a current to the heaters 14. A passivation layer 18 is formed on the heaters 14 and the electrodes 16 to protect the heaters 14 and the electrodes 16. The passivation layer 18 may be formed of a silicon oxide or a silicon nitride. An Anti-cavitation layer 19 is formed on the passivation layer 18 to protect the heaters 14 from cavitation forces generated when bubbles collapse. The anti-cavitation layer 19 is usually formed of tantalum (Ta).
In the above-described inkjet printhead, however, when a rear surface of the substrate 10 is etched with a dry etching method, such as an induced coupled plasma (ICP) etching method, to form the ink feed hole 11, the substrate 10 can be overetched or underetched depending on a position of the substrate 10. In this case, the ink feed hole 10 is non-uniformly formed in the substrate 10, making ink supply to the ink chambers 22 unstable.